Ammunition Science: Rimfire Cartridge Cases

Here's what you need to know about the smallest and oldest of cartridge offerings.

by
posted on July 15, 2022
big pile of loose .22-caliber cartridges
Rimfire cartridge cases have been in continuous production since the mid-1850s, making this type of self-contained cartridge the oldest in production. In the 1800s, there were many calibers of rimfire ammunition, ranging from the humble .22 Short to massive .50-caliber examples. Presently, new .17-caliber rounds have joined traditional .22 cartridges as commercially loaded rimfire offerings.

In concept, the rimfire cartridge is elegantly simple. A one-piece cartridge case is drawn from thin brass and formed with a hollow rim. Priming compound is forced into the rim by centrifugal force from spinning. The primed case is then charged with powder and a bullet seated in the case mouth. To provide sufficient bullet push and pull, the bullet is crimped securely into the case mouth. When the firing pin of hte rifle strikes the thin brass rim, it crushes the hollow rim and ignites the priming mixture within. There is no anvil or separate primer cap.

However, the thin brass rimfire case is weak and will not withstand high breech pressures. Ignition is also weak, resulting in a very inefficient powder burn. However, the rimfire case is cheap and easy to manufacture. When loaded to moderate breech pressures within its strength limitations, the rimfire cartridge has and will continue to provide generations of shooters with low-cost practice, training and small-game hunting capability.

Latest

life.jpg
life.jpg

Trigger Control: How to Make Every Shot Count

From tactical to smallbore competition to big game, success depends on trigger control.

3 Welcome Surprises of Concealed Carry

What the author thought were invisible hurdles to CCW turned out to be welcome surprises ... you may find the same!

11 Things You Need In Your Survival Kit

Nobody ever plans to get lost in the woods; it just happens...and it can happen even to experienced outdoors people.

Rising Shooting Stars: Benjamin Holliger

He made the Top 20 at the 2022 National Matches ... at the age of just 15. What are his secrets?

Fun Friday: Pulp Fiction "Pumpkin" Revolver

A Hollywood moment that subverts the "Chekhov's Gun" trope...or does it?

5 Reasons To Wear Ear Protection Even While Hunting

The face of hunting has changed, so the face of hunters ought to as well.

Interests



Get the best of NRA Family delivered to your inbox.